The invention relates to physiologic monitoring systems and methods, and in particular to physiologic monitors.
Physiological monitoring instruments are used to measure a number of patient vital signs, including blood oxygen level, body temperature, respiration rate, and electrical activity for electrocardiogram (ECG) or electroencephalogram (EEG) measurements. In a common design used to perform ECG measurements, a number of electrocardiograph leads are connected to the patient's skin. Voltage variations are recorded over a period of time, and the resulting signals are processed, stored, and interpreted. The ECG signals of interest may be considerably lower in magnitude than environmental electrical noise levels generated by power lines, fluorescent lights, neighboring electrical devices, or electrolytic effects at the interface between the ECG leads and the patient's skin. The electrical signals sensed by the leads are commonly amplified and filtered in order to generate useful data.
A Holter monitor is an ambulatory electrocardiography device that allows heart monitoring for many hours or even days. Typical Holter monitors employ three to seven leads attached to a subject's skin. The monitor is commonly carried in a pocket or attached to a belt, and keeps a log of the heart's activity during a recording period.
A number of U.S. patents describe physiologic monitors, including portable ECG monitors. For example, in U.S. Pat. No. 5,701,894, Cherry et al. describe an ambulatory physiological computer recorder that includes multiple selective plug-and-play signal input conditioners, a microprocessor system with operating and analyzing software, and a removable memory module for data storage. System sensors may include electrodes for ECG, as well as sensors for measuring body temperature, respiration, skin conductance, and acceleration, among others.
In U.S. Pat. No. 6,198,394, Jacobsen et al. describe a system for remotely monitoring personnel status, including a plurality of sensors disposable on a soldier or other person for developing signals to determine the person's physiological status. Jacobsen et al. describe a wearable sensor unit including multiple sensors and a master controller or processor. Jacobsen et al. also describe employing a wrist sensor/display unit which may include multiple sensors and a controller connected to the sensors. The wrist unit is used in conjunction with a soldier unit carried by a soldier. The soldier unit also includes a controller, sensors, and other devices such as a global positioning system (GPS) device.
In U.S. Pat. No. 6,454,708, Ferguson et al. describe a system for monitoring health parameters and capturing data from a subject. The system includes a cordless sensor band with sensors for measuring full waveform ECG, full waveform respiration, skin temperature, and motion, and a connector which accepts a memory card or a smart card for storage of measured data.